Many applications require devices for accurately and rapidly controlling motion and positioning of a component, which may be relatively small and often delicate, of a mechanical, opto-mechanical and/or electromechanical system. For example, optical systems for use with cameras incorporated in cell phones often require transport systems for accurately moving and controlling the position of lenses and/or other components of the optical systems to provide various focusing and zooming functions. As cell phones become smaller and room available for these cameras shrinks, constraints on the size of transport systems for controlling position of the lenses and/or components, and accuracy and speed with which the transport systems perform, in general become more stringent.
Various piezoelectric motors are controllable to provide accurately controlled amounts of kinetic energy to mechanical systems. For example, U.S. Pat. No. 5,616,980 to Zumeris et al, and PCT Publication WO 00/74153 entitled “Multilayer Piezoelectric Motor” describe piezoelectric motors that are capable of transmitting accurately controlled amounts of kinetic energy to move and position objects. Piezoelectric motors described in the referenced patent and PCT Publication comprise a relatively thin rectangular piezoelectric vibrator having large parallel face surfaces and narrow short and long edge surfaces. Optionally, a surface region of a short edge of the vibrator or a surface of a “friction nub” on a short edge of the vibrator functions as a motor coupling surface that is pressed to a contact surface of a moveable body. Electrodes on the face surfaces of the vibrator or, for piezoelectric motors described in WO 00/74153, on face surfaces of layers of the vibrator, are electrified to excite vibrations in the motor's friction nub that transmit kinetic energy to the moveable body via the body's contact surface. PCT Publication PCT/IL00/00698 entitled “Piezoelectric Motors and Motor Driving Configurations” describes various piezoelectric motors and methods of coupling such motors to rotate moveable bodies. PCT Application PCT/IL03/00603 entitled “High Resolution Piezoelectric Motor” describes piezoelectric motors and methods of operating piezoelectric motors to position an object with relatively high accuracy. The disclosures of all the above referenced documents are incorporated herein by reference.